ACK/Cmnt: [SRU B/D/E/F V2 1/1] efi: efi_get_memory_map -- increase map headroom

Stefan Bader stefan.bader at canonical.com
Tue Nov 12 14:36:42 UTC 2019


On 08.11.19 11:25, Andy Whitcroft wrote:
> We are seeing some EFI based machines failing to boot hard in the EFI
> stub:
> 
>     exit_boot() failed!
>     efi_main() failed!
> 
> This seems to occur when the bootloader (grub2 in this case) has had
> to manipulate some additional files due to a change in the way MAAS
> boots the machines.  We tracked this down to the memory map dance
> efi_get_memory_map().  Basically we attempt to close boot services and
> it informs us it cannot do so because it failed to record the updated
> memory map.  This occurs when there is insufficient space in the passed
> memory map buffer to record changes during the operation.  At the point
> when this occurs we are unable to call the allocation functions to
> reallocate the buffer so we panic.
> 
> To avoid this we allocate some additional entries in the buffer to cover
> any additional entries.  This headroom is currently insufficient for
> these machines under this use case.  Increase EFI_MMAP_NR_SLACK_SLOTS to
> provide space for more memory map modifications.
> 
> BugLink: https://bugs.launchpad.net/bugs/1851810
> Signed-off-by: Andy Whitcroft <apw at canonical.com>
Acked-by: Stefan Bader <stefan.bader at canonical.com>
> ---

with added "UBUNTU: SAUCE ..." prefix as Seth pointed out.

>  drivers/firmware/efi/libstub/efi-stub-helper.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/firmware/efi/libstub/efi-stub-helper.c b/drivers/firmware/efi/libstub/efi-stub-helper.c
> index 39f87e6dac5c..957dff5a26a2 100644
> --- a/drivers/firmware/efi/libstub/efi-stub-helper.c
> +++ b/drivers/firmware/efi/libstub/efi-stub-helper.c
> @@ -49,7 +49,7 @@ int __pure novamap(void)
>  	return __novamap;
>  }
>  
> -#define EFI_MMAP_NR_SLACK_SLOTS	8
> +#define EFI_MMAP_NR_SLACK_SLOTS	16
>  
>  struct file_info {
>  	efi_file_handle_t *handle;
> 


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